here's a big pile of questions: need setup advice

[lincpimp]

Well, the faster you spin the motor, the less life you will get out of the bearings. Plus you do place more load on the rotor and the case. Power is not really an issue with a neu 1515. I would say that a 2000kv neu motor would be fine on 6s. Plus, you run into issues gearing a motor turning more than 40k rpm low enough to keep speeds around 40-45mph. I have a buggy that has a hacker c50 8l on 4s lipo. It spins around 45k rpm. I have to run an 11t pinion to get speeds around 40-43mph. That is the smallest pinion I can fit before the motor hits the center diff outdrive.